1978 C&c 38
I own a 1978 C&C 38 which I purchased from the second owner in 2000. Mine has a Volvo diesel which was an option at the time. We do a good deal of racing under PHRF as well as using the boat as our family "summer cabin". It is a great all-round boat: comfortable, strong and fast.
The sailing qualities are excellent. Upwind it can be balanced to track "hands off". Downwind it is easy to keep under the spinnaker, even when doing 12kts in 25kts+ of true breeze. It exhibits little of the tendency that other IOR boats of this vintage have to spin out when pressed downwind.
There is plenty of room for cruising amenities like hot water, pressure water, a fridge, etc. It's proven very comfortable for week-long cruises for our family of four plus a couple of guests or two couples.
Structurally the boat has held up very well. There are no blisters and the hull is extremely fair. There are a few stress cracks in the gelcoat on the deck at sharp corners, nothing serious. I understand that both the deck and hull are balsa-cored. If the hull you are looking at is blister free and the core is dry I'd say that everything else is easily fixable or refinishable.
The boat is not particularly tender, but you can bury the rail in 15kts and above. There are two things you can do: 1) get excess weight out of the mast and running rigging; and 2) reef down when the breeze is up.
Before I bought mine I corresponded with a couple from Sweden who had purchased a C&C38 on Lake Ontario, sailed it to Sweden for refit and were at that time in New Zealand about half-way through their circumnavigation. They testified that the boat was a fine passagemaker in all kinds of blue-water conditions, some of them quite extreme.
Hope this helps!